DESCRIPTION: (Applicant's Description) This Core is designed to meet the needs of all three research projects on this program project grant. The core has two components. One will provide service and the other will develop future technologies. The service component seeks to accomplish two goals. One goal is to provide chimerism analyses in dogs and human patients after stem cell transplantation using microsatellite marker polymorphism. These serve to evaluate hematopoietic engraftation in studies carried out under all three research projects. The second goal is to provide canine histocompatibility typing (Dog leukocyte Antigen typing) for Projects 1 and 3 with the aim of selecting littermate donor-recipient pairs for transplantation. The research component will serve future studies in projects 1 and 2 which will include unrelated donor-recipient pairs that are matched for the major canine histocompatibility complex (MHC) antigens. The research component of the core also pursues two goals. The first involves the development of a polymerase chain reaction-single strand conformational polymorphism assay for typing polymorphic clas I genes (as has already been done for class II genes). The second goal involves screening a Bacterial Artificial Chromosome (BAC) library to locate previously uncharacterized polymorphic MHC genes which may play important roles in host-versus-graft and graft-versus-host reactions after unrelated stem cell transplantation.